The present invention relates to an electromagnetic relay, and more particularly relates to a low profile type of electromagnetic relay which is particularly suitable for being mounted directly to a printed circuit board.
There are various conventional types of electromagnetic relays, and in the recent prior art various types of such electromagnetic relays have been proposed for being directly mounted to printed circuit boards. It is desirable that such a directly mounted electromagnetic relay should be low in height, so that it may be of approximately the same height as other components mounted on the printed circuit board; and such a relay should as a matter of course be accurate and stable in action. Particularly, with a directly mounted electromagnetic relay of the type categorized as a SMD (surface mounted device), the desirability of reduction of the overall height is very strong because its terminals are directly soldered to the printed circuit board. Further, because such a directly mounted electromagnetic relay will inevitably be directly exposed to heat from various components mounted on the printed circuit board, it is desirable that it should be able to tolerate quite high temperatures.
As a typical conventional electromagnetic relay adapted to be mounted on a printed circuit board, there is the one disclosed in Japanese Patent Laying Open Publication No. 57-30232. According to this prior art type of electromagnetic relay, since its contact drive element or armature member is located between the base and the driving electromagnet device, or in other words these elements are stacked one over the other, there arose the problem that the overall height of the relay tended to be greater than desired. Furthermore, since its contact drive element or armature member was planar, it had a tendency to warp as a result of temperature variations. Furthermore, the action of the contact drive element or armature member has a tendency not to be properly stable, due to the fact that the support shaft is rather short. These problems tended to contribute to the instability of the action of such a prior art electromagnetic relay.